Liquid insulating composition



Pate ed Jan- 1 1938 BESTAVAILABLE COP uoornmsom'mvc COMPOSITIO Frank M. Clark, Pittsfield, Mass, assignor to Gen-- eral Electric Company, a corporation of New York No Drawing. Original application May 25, 1935, Serial No. 23,403. Divided and this application September 24, 1936, Serial N0. 102,985

5 Claims. '(Cl. 252-1) The present invention comprises an improvement in dielectric compositions of the type described in my prior Patents 1,931,373 and 1,931,- 455,- patented .October 17, 1933, namely, halogen- 5 ated aryl compounds for use as dielectric and insulating materials in electric devices. It is the object of my present invention to further improve the chemical stability of such compositions.

Halogenated aryl compounds have been found to be chemically stable, no appreciable decomposition occurring under ordinary conditions even when such compounds are in direct contact with a metal. However, it has been found that when 'such compounds come in direct contact with an electric arc that some decomposition occurs accompanied by the evolution of hydrogen halide, as for example hydrogen chloride in the case of chlorinated compounds. In devices such as electric transformers in which arcing occurs no only under exceptional and abnormal conditions the possibility of decomposition of chlorinated aryl hydrocarbon compounds is not a particularly troublesome contingency. However, in some electric devices, as for example electric circuit breakers, in which arcing occurs incidental to their normal operation the evolution of halogen halide presents'a serious handicap 'to the use of such compositions. While hydrogen halide in any case is an undesirable compound to have 39 in contact with electrical apparatus, it is particularly deleterious in the presence of moisture. For example, when moisture is present the hydrogen halide tends to become emulsified in the hydrocarbon composition. It decreases the dielectric 3 5 strength of the composition in which it is present and may cause damage as by corrosion of metal parts of apparatus in which such composition is used.

It is the object of my present invention to 40 render such hydrogen halide decomposition products innocuous. In accordance with my invention halogenated hydrocarbon dielectric and insulating compositions are mixed with a chemically-unsaturated fixative which is miscible with such hydrocarbon and is capable of combining with hydrogen halide and perhaps other decomposition products, to form a material which is non-corrosive in the electrical devices or wherever such hydrocarbon compounds may be used.

Fixatives capable of use in accordance with my invention are unsaturated hydrocarbon compounds, such as terpenes, camphors and ethereal oils.

The outstanding useful property of compounds here under consideration is their aflinity for hydrogen chloride, no solid precipitate being formed and no deleterious or poisonous gases being evolved. Apparently, a harmless addition product is formed whichdissolves in the composition.

As above indicated, the fixatives are compounded with one or more liquid dielectric materials, such for example as chlorinated diphenyl, trichlor benzene, chlorinated diphenyl oxide, chlorinated naphthalene, chlorinated diphenyl methane, and others which may be termed genrically chlorinated phenyl compounds.

Chemically unsaturated compounds which may be used, are usually classed chemically as terpenes and camphors. Representative compounds of this class are (a) the open chain oleflnic terpenes and camphors (isoprene, citronellal, citral, geraniol) (b) monocyclic terpenes and camphors (dipentene, terpinene), (c) complex cyclic terpenes and camphors (pinene). -Certain ethereal oils consisting-chiefly of compounds of this type may be employed in accordance with this invention. Such oils are oil of turpentine, oil oi citron, orange oil,,and oil of thyme.

When such fixatives are used in the halogenated aromatic compositions it is usually suificient to employ about 1 to '10 percent 0! the fixative ingredient, ordinarily 5 per cent being a suitable amount. A. materially larger proportion of unhalogenated fixative may impart some degree of inflammability to the otherwise noninflammable composition. The determining factor is the proportion of hydrogen which is given 05 by these What I claim as new and desire to secure-by Letters Patent of the United States is:

l. .A' composition of matter comprising as substantlal ingredients halogenated aryl compound and a substantial fixative ingredient of the class consisting of about one to ten per cent terpenes, camphors and ethereal oils.

2. A composition of matter comprising as substantial ingredients chlorinated aryl compound thyme.

3. A dielectric and insulating composition ma'de up of a preponderant proportionfof chlorinated sryl constituent and about one to ten percent 10o! turpentineoil. l v

and at least about one per cent-i0: -materia1 in the class consisting of open chain oleiinic .terpenes and camphors; monocyclic terpenes and camphors; complex cyclic terpenes and camphors; and oils of turpentine, citron', orange and 4. A dielectric and insulating composition made up of a. preponderant proportion of chlorinated .aryl constituent and about one to ten per cent oipinene.

5. A composition of matter including a preponderant ingredient chlorinated di-phenyl and vabout-1 to 10 percent of a fixative of the class consisting of terpenes, camphors and ethereal oils.-

- FRANK M. CLARK. 

